When image tracking is performed on an image sequence which includes a series of images captured from the same object during the expansion, contraction or another movement period of the object, sometimes, template matching is used to perform a two-dimensional movement tracking. By performing template matching on each part in a region of interest across images, the movement of the region of interest can be tracked. Occasionally, due to the high-speed of the object, when template matching is performed on a specific image with a part of a former image as a template, it is difficult to find, within a search range, a part of the specific image matching with the part in the former image.
Thus, a technology is desired which is capable of addressing the problem above.